Preheat oven to 380 degrees Fahrenheit.
In a bowl, sift the flour, baking powder, and salt. Set aside.
Take one orange, cut in half and press the juice out of both halves of the orange. Strain liquid into a medium bowl. Make sure all seeds are removed from the freshly squeezed juice.
Peel the other orange and cut it into bite-sized chunks. Add it to the bowl with juice and set aside.
Add egg, sugar, milk, orange pieces, fresh orange juice and butter into a mixing bowl. With a hand mixer or a whisk, mix until all the ingredients are well combined.
Pour the liquid mixture over the dry ingredients and gently mix with a large spoon. Do not over mix.
Gently fold in the chocolate chips.
Spoon the batter into silicone or paper-lined muffin pans until they are about ¾ full.
Bake on center rack in oven at 380°F for 20 to 25 minutes.